This invention relates to a pressure filter insertable in a centrifuge tube for filtering by means of centrifugal force.
A standard one-piece centrifuge tube which is commercially available for separating millileter/microliter liquid samples consists of a plastic tube having a closed conical-shaped bottom and an open top, a cap for releasably sealing the open top, and a flexible connecting member extending between the tube and cap. In use, the centrifuge tube is filled with a mixture or suspension of materials of closely similar densities and placed in a complimentary-shaped slot of a centrifuge tube holder. By spinning the tube in the centrifuge, the application of centrifugal force causes the mixture of materials to separate by specific density. The centrifuge chamber may revolve at speeds of 10,000 rpm or more to impart a force up to 17,000 times that gravity. The smaller the difference in density, the greater is the force required for separation. Because the tubes are held at an angle in the tube holder, with the lower end of the tube further from the center line of the chamber than the upper end, the materials of higher density collect in the lower portion of the tube while those of lower density are concentrated at or near the upper portion of the tube. This technique is used effectively in a number of biological and industrial operations, such as separation of the components of blood.
Filtration involves the separation of solutes and particles larger than a specified filter "cut of" from the solvent and smaller molecules which pass through the filter. A pressure filter requires the application of force to cause liquid to flow through the filter. Typically such force is provided by ejecting the liquid through a syringe or by applying a vacuum. Filtration is also used effectively in a number of biological and industrial operations.
It is an object of the present invention to provide a pressure filter which is insertable within a centrifuge tube for filtering materials by means of centrifugal force.
It is another object of this invention to provide a filter tube for use with a standard centrifuge tube having a cap wherein the filter tube is insertable into an upper portion of the centrifuge tube and is sealed and held in place in the centrifuge tube by the cap.